JPH06118731A - Electrophotographic lithographic printing original plate - Google Patents

Abstract

PURPOSE:To reduce the elongation of the plate due to moistening water added in printing and to improve the printing durability by specifying the gradient of the regression line showing the relation between the natural logarithm of pressure and distortion when a substrate provided with a photoconductive layer is compressed. CONSTITUTION:A photoconductive layer contg. a photoconductive substance is provided on a substrate to constitute a lithographic printing original plate. In this case, the gradient K of a regression line showing the relation between the natural logarithm of pressure and distortion when the substrate is compressed is expressed by the equation, and K is controlled to >=80. In the equation, P is the pressure in kg/cm<2> exerted on the substrate, P0 is the pressure in kg/ cm when the distortion of the substrate is zero, and E is the distortion of substrate. The substrate should be calendered to increase the density when paper is used for the substrate in order to obtain the substrate having >=80K value. When this substrate is used, the distortion in the thickness and facial directions is reduced, even if the original plate is compressed between the plate shell and blanket by the nip pressure in printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic lithographic printing original plate having a small plate elongation during printing and excellent printing durability.

[0002]

2. Description of the Related Art Generally, an electrophotographic lithographic printing plate precursor is constructed by providing a photoconductive layer containing an inorganic or organic photo-semiconductor on a support having properties such as conductivity and water resistance. As the body, paper, metal foil, film,
Alternatively, a sheet-like substance such as a complex thereof is used.

When paper is used as a support, a wet strength agent such as a polyamide resin, a polyamide epichlorohydrin resin or a melamine formalin resin enhances water resistance, and sodium chloride or chloride is used to obtain a better electrophotographic image. Inorganic electrolytes such as potassium and calcium chloride and organic polymer electrolytes such as quaternary ammonium salts are added.

Instead of paper, a metal foil of aluminum, zinc, copper or the like is used instead of vinyl acetate resin, acrylic resin,
Metal foil laminated paper adhered with an adhesive such as an emulsion of polyolefin resin or polyurethane resin or an organic solvent solution, conductive film laminated paper adhered with a conductive treated polyester film with the above adhesive, conductive If a conductive polyolefin resin laminated paper obtained by extruding and laminating a polyolefin resin containing a conductive substance is used as a support, elongation and tensile strength when wet can be improved, and an electrophotographic lithographic printing plate precursor having a small plate elongation can be obtained. Obtainable.

However, even if an electrophotographic lithographic printing plate precursor is produced using such a support, the plate elongation is avoided by addition of dampening water during printing or the nip pressure between the plate cylinder and the blanket. However, there are problems such as plate wrinkles, misregistration of printed matter, and rounded dimensions of ruled lines.

[0006]

SUMMARY OF THE INVENTION The present invention has a small plate elongation due to addition of dampening water during printing, a nip pressure between a plate cylinder and a blanket, etc., which cannot be realized by such a conventional technique. It is intended to provide an electrophotographic lithographic printing plate precursor having good printing durability.

[0007]

Means for Solving the Problems As a result of examination by the present inventors of the relationship between the amount of strain when the support is compressed and the plate elongation of the electrophotographic lithographic printing plate, there is a close relationship between the two. I found it. That is, when the support is compressed,
It was found that the smaller the strain in the thickness direction, the smaller the strain in the plane direction and the smaller the plate elongation at the time of printing of the electrophotographic lithographic printing plate precursor. Then, as a result of a more detailed examination, the slope of the regression line showing the relationship between the natural logarithm of the pressure and the strain when the support was compressed,
When an electrophotographic lithographic printing plate precursor was produced using a support having a K value of (Equation 1) of 80 or more, it was found that the plate elongation due to the nip pressure between the plate cylinder and the blanket during printing can be suppressed to be small. The present invention has been completed.

[0008]

## EQU2 ## K = log _e (P / P ₀ ) / E (Equation 1) where P is the pressure applied to the support (kg / cm ² ), P ₀
Is the pressure applied to the support when the strain of the support is 0 (kg /
cm ² ), E is the strain of the support.

In the present invention, any material can be used for the support as long as it is a sheet-like substance having water resistance and appropriate conductivity, and examples thereof include paper, metal foil, film and composites thereof. Etc. can be used. Among them, metal foil laminated paper obtained by bonding paper and metal foil such as aluminum, zinc, and copper with an adhesive such as vinyl acetate resin, acrylic resin, polyolefin resin, polyurethane resin emulsion or organic solvent solution is used. Since it is lightweight and has high tensile strength, plate elongation during printing can be suppressed to a low level.

In the present invention, in order to suppress the plate elongation at the time of printing to a small value, the K value of the above equation 1 which is the slope of the regression line showing the relationship between the natural logarithm of the pressure and the strain when the support is compressed. It is necessary to prepare an electrophotographic lithographic printing plate precursor using a support having a ratio of 80 or more. When the K value of the support is less than 80, when the electrophotographic lithographic printing plate precursor is compressed due to the nip pressure between the plate cylinder and the blanket during printing, large distortion occurs in the thickness direction and the plane direction, and The growth increases.

In the present invention, it is effective to increase the density of the support in order to obtain a support having a K value shown in the equation 1 of 80 or more. In particular, when using paper, it is desirable to increase the density by carrying out calendering with a machine calender, super calender, soft calender or the like.

In the present invention, in order to increase the water resistance of the support, an intermediate layer may be provided on the side of the support on which the image receiving layer is provided or a backing layer may be provided on the side opposite to the image receiving layer. Normal,
Synthetic resin emulsion is used for the intermediate layer or back coating layer.
If necessary, it is mixed with a pigment such as clay, sericite or calcium carbonate, a water-soluble resin such as starch or polyvinyl alcohol, a conductive agent, a cross-linking agent and the like and applied.

In the present invention, the image receiving layer refers to an image formed by an electrophotographic method, and contains an optical semiconductor as a basic component thereof. Usually zinc oxide,
An inorganic optical semiconductor such as titanium dioxide or cadmium sulfide dispersed in an insulating adhesive resin, or an organic optical semiconductor such as polyvinylcarbazole is used.

[0014]

In the present invention, it is the slope of the regression line showing the relationship between the natural logarithm of the pressure and the strain when the support is compressed,
Use of a support having a K value of 80 or more in Equation 1 suppresses distortion in the thickness direction and the plane direction to a small level even if the electrophotographic lithographic printing plate precursor is compressed by the nip pressure between the plate cylinder and the blanket during printing. Therefore, an electrophotographic lithographic printing plate precursor having a small plate elongation and excellent printing durability can be obtained.

[0015]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The parts and% shown below are based on weight.

Example 1 A coating solution of oxidized starch, styrene resin sizing agent and sodium chloride was applied to both sides of a high-quality paper having a basis weight of 50 g / m ^{2 so} that the dry coating amount was 1.9 g / m ^2. After applying and drying using a size press device, smoothing treatment was performed using a machine calendar.

Next, on one surface of the aluminum foil having a thickness of 10 μm,
An adhesive for dry lamination having the following composition was applied so that the dry coating amount would be 3.0 g / m ² , and laminated on this paper. After this aluminum foil laminated paper is left at room temperature for 2 days to be aged at room temperature, a dry laminating adhesive having the following composition is applied to the other aluminum foil surface so that the dry coating amount becomes 3.0 g / m ^2. And then laminated again with this base paper. This aluminum foil laminated paper at room temperature 2
It was left to stand for a day for aging at room temperature. (Adhesive composition for dry laminate) Polyester polyol resin (BLS-PC21, manufactured by Toyo Morton, solid content 35%) 15 parts Polyisocyanate (CAT-100, manufactured by Toyo Morton, solid content 50%) 1 part Ethyl acetate 3 parts

Then, an intermediate layer having the following composition was coated on one side of this aluminum foil laminated paper so that the dry coating amount was 15 g / m ² , and dried at 150 ° C. for 20 seconds. (Intermediate layer composition) Inorganic pigment containing sericite (Dikelite TMC, product of Dextrite Chemical Co., Ltd., 50% aqueous dispersion) 100 parts Carboxyl-modified SBR latex (solid content 48%) 50 parts Melamine resin initial condensate (Smireth Resin-613, Sumitomo Chemical, solid content 80%) 4 parts Organic amine salt catalyst (Sumitex Accelerator ACX-P, Sumitomo Chemical, solid content 35%) 0.4 parts Ammonium polystyrene sulfonate (solid content 30%) 4 parts

On the side opposite to the intermediate layer of this aluminum foil laminated paper, a back coating layer having the following composition was applied in a dry coating amount of 15 g.
/ M ² and applied, and dried at 150 ° C for 20 seconds. (Backcoat layer composition) Kaolin (Hydraspar, manufactured by Huber, 50% aqueous dispersion) 100 parts Inorganic pigment containing sericite (Sikelite TMC, manufactured by Siclaite Chemical, 50% aqueous dispersion) 100 parts Oxidized starch (25%) Aqueous solution) 60 parts Carboxyl-modified SBR latex (solid content 48%) 150 parts Ammonium polystyrene sulfonate (solid content 30%) 6 parts Melamine resin initial condensate (Sumirez Resin-613, Sumitomo Chemical, solid content 80%) 4 parts

Then, this aluminum foil laminated paper was supercalendered and then Tensilon CR-700 was used.
Using a 0 / UTM universal tester (manufactured by Toyo Baldwin), the relationship between pressure and strain when the support was compressed was obtained, and the K value, which is the slope of the regression line showing the relationship between the natural logarithm of pressure and strain, was calculated as above. It was 88 when calculated by the mathematical formula 1.

Further, a photoconductive layer having the following composition was coated on the surface of the intermediate layer of the support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare a printing original plate. . (Photoconductive layer composition) Zinc oxide for electrophotography 200 parts Acrylic resin (50% liquid) 80 parts Rose Bengal (2% methanol solution) 15 parts Xylene 250 parts

Example 2 A coating solution comprising oxidized starch, styrene resin sizing agent and sodium chloride was applied to both sides of a high-quality paper having a basis weight of 100 g / m ^{2 so} that the dry coating amount was 2.2 g / m ^2. After applying and drying using a size press device, smoothing treatment was performed using a machine calendar.

Then, the intermediate layer of Example 1 was coated on one side of the surface-treated fine paper to a dry coating amount of 15 g / m ² and dried at 150 ° C. for 20 seconds.

The backing layer of Example 1 was coated on the side opposite to the intermediate layer of this one-side coated paper so that the dry coating amount was 15 g / m ² , and dried at 150 ° C. for 20 seconds.

After the double-coated paper was supercalendered, the K value was calculated in the same manner as in Example 1, and it was 86.

Further, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of the support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare an electrophotographic lithographic printing plate precursor. Was produced.

Example 3 The aluminum foil laminated paper of Example 1 was supercalendered and the K value was calculated in the same manner as in Example 1 to find 182.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of the support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to obtain an electrophotographic lithographic printing plate precursor. It was made.

Example 4 The double-sided coated paper of Example 2 was supercalendered and K value was calculated in the same manner as in Example 1.
It was 7.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of this support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare an electrophotographic lithographic printing plate precursor. Was produced.

Comparative Example 1 After the aluminum foil laminated paper of Example 1 was supercalendered, the K value was calculated in the same manner as in Example 1 and it was 74.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of this support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare an electrophotographic lithographic printing plate precursor. Was produced.

Comparative Example 2 After the double-sided coated paper of Example 2 was supercalendered, the K value was calculated in the same manner as in Example 1 and found to be 72.
Met.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of this support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare an electrophotographic lithographic printing plate precursor. Was produced.

Comparative Example 3 The K value was 47 when the K value was calculated in the same manner as in Example 1 without supercalendering the aluminum foil laminated paper of Example 1.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of the support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to prepare an electrophotographic lithographic printing plate precursor. It was made.

Comparative Example 4 The K value was calculated in the same manner as in Example 1 except that the double-sided coated paper of Example 2 was not subjected to the super calendar treatment.
Met.

Then, the photoconductive layer of Example 1 was coated on the surface of the intermediate layer of the support so that the dry coating amount was 20 g / m ^2, and dried at 90 ° C. for 30 seconds to obtain an electrophotographic lithographic printing plate precursor. It was made.

These electrophotographic lithographic printing plates were prepared at 20 ° C.
Under the condition of 65% RH, plate making was carried out by an electrophotographic plate making machine Diafax EP-31V (made by Mitsubishi Paper Mills, a plate making machine for liquid development).

Next, desensitization treatment was carried out with an etch liquid Diafax LOM-OHII (manufactured by Mitsubishi Paper Mills) for an electrophotographic offset master, and the offset printing machine Toko Model was used.
Using 810 (manufactured by Tokyo Aviation Keiki Co., Ltd.), printing was carried out by horizontally laying the electrophotographic planographic printing original plate so that the machine direction of the support was horizontal.

The evaluation results are collectively shown in Table 1. The plate elongation in the table is obtained by measuring the distance between the register marks before printing and after printing 5000 sheets on a scale, and calculating the ratio of the difference between the register marks before and after printing to the distance between the register marks before printing. evaluated.

[0042]

[Table 1]

From the results in Table 1, in Examples 1 to 4, since the K value shown in Formula 1 was large, the plate elongation during printing was small. In Comparative Examples 1 to 4, since the K value shown in Formula 1 is small, when the electrophotographic lithographic printing plate precursor is compressed by the nip pressure between the plate cylinder and the blanket at the time of printing, it is large in the thickness direction and the plane direction. Distortion occurred and plate elongation increased.

[0044]

As is apparent from the above description, according to the present invention, it is possible to suppress the plate elongation due to the nip pressure between the plate cylinder and the blanket during printing to be small, and the printing durability is good. An original electrophotographic planographic printing plate can be obtained.

Claims (1)

[Claims] 1. An electrophotographic lithographic printing plate precursor having a photoconductive layer containing a photoconductive substance on a support, the slope of a regression line showing the relationship between the natural logarithm of the pressure when the support is compressed and the strain. An electrophotographic lithographic printing plate precursor having a K value represented by the following mathematical formula 1 (Formula 1) and having a K value of 80 or more. ## EQU1 ## K = log _e (P / P ₀ ) / E (Equation 1) where P is the pressure applied to the support (kg / cm ² ), P ₀
Is the pressure applied to the support when the strain of the support is 0 (kg /
cm ² ), E is the strain of the support.